The present invention relates generally to tie layers that may be employed to adhesively bond plastic film layers and/or sheets one to another to form composite laminate structures. More specifically, the present invention relates to composite laminate structures that are particularly usefully employed in the manufacture of automotive components (especially exterior automotive trim components).
It is notoriously well known to apply automotive trim components made of plastics material to the exterior of automotive vehicles, such as cars, trucks, vans and the like. Examples of such trim components include accent stripes, side door bumper elements, claddings, wheel covers, grills, and bumper fascia. Moreover, other automotive components that are made from plastics, such as automotive body panels (e.g., door side panels) and the like are known.
Problems have been encountered in the past when the color of automotive components formed from plastics materials is attempted to be matched or coordinated with the overall body color. For example, such components have typically been painted with a final xe2x80x9cclear coatxe2x80x9d being applied for purpose of protecting the underlying colored or pigmented paint coat.
It has recently been proposed in U.S. Pat. No. 6,187,233 B1 issued on Feb. 13, 2001 (the entire content of which is expressly incorporated hereinto by reference), to provide a color pigmented thermoplastic layer which is calendered into a laminate structure with a transparent clear coat layer. The laminate is then subsequently vacuum-formed into a three dimensional shaped structure approximating the final shape of the final automotive component. In especially preferred embodiments, the color pigmented layer is a thermoplastic polyolefin (TPO), while the clear coat layer is a fluorinated thermoplastic material, such as polyvinyl fluoride (PVF).
While the techniques described in the above-noted U.S. ""233 patent are satisfactory, certain improvements therein are still desirable. For example, it would be highly desirable if the bonding strength between the color pigmented and clear coat layers could be enhanced. It is towards providing such improvements that the present invention is directed.
Broadly, the present invention is embodied in laminates which include a thermoplastic substrate layer, a clear coat layer, and a tie layer. The tie layer most preferably includes an adhesive-enhancing effective amount of a maleic anhydride grafted styrenic block copolymer which adhesively bonds the substrate and clear coat layers one to another. Most preferably, the tie layer is a maleic anhydride grafted block copolymer comprised of styrene units and lower olefinic (e.g., C2-C5) copolymeric units, such as ethylene-propylene units, ethylene-butylene units and the like. The laminate may be employed to manufacture a variety of shaped articles, most preferably automotive trim components.
These and other aspects and advantages will become more apparent after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof.